Luther’s concern throughout the book [On War Against the Turks] is to teach men how to fight with a clear conscience. In so doing he develops two major points. There are, he says, only two men who may properly fight the Turk [Muslims, in our terminology]. The first of these is the Christian, who by prayer, repentance, and reform of life takes the rod of anger out of God’s hand and compels the Turk to stand on his own strength. The second man who may wage war is the emperor. The Turk has wrongfully attacked the emperor’s subjects, and by virtue of the office to which God has appointed him, the emperor is duty-bound to protect and defend the subjects with whose care God has entrusted him.*
It’s a pretty sharp booklet. Theologically, it gives priority to prayer and repentance so that war is avoided because God’s wrath is assuaged. A brilliant theological move really. And it was published on 9 October, 1528.
*Martin Luther, Luther’s Works, Vol. 46: The Christian in Society III, ed. Jaroslav Jan Pelikan, Hilton C. Oswald, and Helmut T. Lehmann, vol. 46 (Philadelphia: Fortress Press, 1999), 159.